The classification of particles according to their size and/or weight is often used in mineral processing. In order to classify these particles it is common to locate the particles in a solution to form a slurry. This slurry is then passed through various types of equipment in order to separate the particles into different sizes and/or densities.
One of these types of equipment is a classifier that separates particles according to their size and/or density. Reflux classifiers typically have a slurry which is fluidised and passed through a plurality of parallel plates, or lamellae, which use gravity to separate solid particles from the liquid. In order to operate the Reflux classifier needs the material being separated to form a fluidised bed, which is the primary form of gravity separation.
However, for low grade minerals, typically high value minerals such as gold or diamonds where head grades are in the order of a few percent or lower, only a relatively small portion of the feed material results in underflow. This results in the Reflux classifier having difficulty forming an effective fluidised bed. In some cases it can take many hours to form a bed and, during this time, no effective separation or concentration occurs, resulting in lost productivity. Furthermore, even once a fluidised bed is achieved, the mineral concentrations are so low that they typically need to be processed multiple times to yield the desired mineral output. This complicates processing, further increasing capital and running costs and further reducing efficiency.
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